The first thing that jumps out at me are the boxed numbers: 0N and 1N. I'm guessing the Clojure implementation can produce a much larger result than the python implementation can - so, apples to oranges. Probably unbox the numbers and you get much more comparable speed.
Also, you should definitely do two things when running speed comparisons: 1. Make sure the JVM flag -server is configured. 2. Test with Criterium. (https://github.com/hugoduncan/criterium) On Wednesday, December 31, 2014 2:03:03 PM UTC-6, Sakis K wrote: > > Hi, > > Clojure newbie here :) I'm reading "Programming Clojure" by Halloway and > Bedra. In the book there is a lazy-seq example of the Fibonacci sequence: > > (defn lazy-seq-fibo > ([] > (concat [0 1] (lazy-seq-fibo 0N 1N))) > ([a b] > (let [n (+ a b)] > (lazy-seq > (cons n (lazy-seq-fibo b n)))))) > > > I like the flexibility of this implementation but I am a bit sceptical > about its performance: > > user=> (time (rem (nth (lazy-seq-fibo) 1000000) 1000)) > "Elapsed time: 53552.014713 msecs" > 875N > > > > Here's a Python implementation taken from > http://en.literateprograms.org/Fibonacci_numbers_%28Python%29 > > def fib(n): > a, b = 0, 1 > for i in range(n): > a, b = b, a + b > return a > > if __name__ == '__main__': > print(fib(1000000) % 1000) > > > time python fib.py > 875 > > real 0m16.609s > user 0m16.475s > sys 0m0.115s > > > 53 vs 17 seconds is a big gap. Is there a way to achieve better > performance in Clojure? Maybe the fact that I executed the code in the REPL > or the Java version that I'm using matters: > java -version > java version "1.7.0_65" > OpenJDK Runtime Environment (IcedTea 2.5.3) (7u71-2.5.3-0ubuntu1) > OpenJDK 64-Bit Server VM (build 24.65-b04, mixed mode) > > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
